Fruit flies at boiling point

IN A world first, researchers have shown that many species of fruit fly won't survive even a modest increase in temperature. Many are close to or beyond their temperature safety margin - and very few have the genetic ability to adapt to climate change.

As Ary Hoffmann of the University of Melbourne's department of genetics put it: ''We were hoping to see potential for adaptation and that didn't happen. Which is bad news. And not just for fruit flies.''

The research - published this week in Proceedings of the National Academy of Sciences, researchers from Monash University, the University of Melbourne and Danish collaborators - is part of an ongoing project to identify signatures of extinction risk, at the genetic level. This will indicate what life forms will be the first-stage losers in a climate of greater extremes - heat, cold and dryness.

A lot of climate research has focused on the delicacy of tropical environments, such as rainforests. ''What this paper shows, worryingly, is that it's very difficult for species that have evolved in more moderate mid-latitude environments to jump into a more extreme environment.''

It's worth noting here that human beings evolved in a more moderate environment.''

Vanessa Kellerman, of Monash University's Molecular Ecology Research Group, said the scientists looked at the heat resistance of 100 different species of fruit flies. ''This involved putting them in a water bath and slowly ramping up the water temperature over a three- or four-hour period until they started literally falling over.''

It was found that only a few species could withstand high temperatures, and that these species were all closely related - and had evolved in a more extreme climate. ''This is suggesting to us that most species don't have the gene to increase their heat resistance. They appear constrained by an evolutionary straitjacket,'' says Dr Kellerman.

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